1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Edward Sze-Tyan Wang.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #include <sys/cdefs.h>
36
37 __FBSDID("$FreeBSD$");
38
39 #ifndef lint
40 static const char sccsid[] = "@(#)forward.c 8.1 (Berkeley) 6/6/93";
41 #endif
42
43 #include <sys/param.h>
44 #include <sys/mount.h>
45 #include <sys/types.h>
46 #include <sys/stat.h>
47 #include <sys/time.h>
48 #include <sys/mman.h>
49 #include <sys/event.h>
50
51 #include <err.h>
52 #include <errno.h>
53 #include <fcntl.h>
54 #include <limits.h>
55 #include <stdio.h>
56 #include <stdlib.h>
57 #include <string.h>
58 #include <unistd.h>
59
60 #include <libcasper.h>
61 #include <casper/cap_fileargs.h>
62
63 #include "extern.h"
64
65 static void rlines(FILE *, const char *fn, off_t, struct stat *);
66 static int show(file_info_t *);
67 static void set_events(file_info_t *files);
68
69 /* defines for inner loop actions */
70 #define USE_SLEEP 0
71 #define USE_KQUEUE 1
72 #define ADD_EVENTS 2
73
74 static struct kevent *ev;
75 static int action = USE_SLEEP;
76 static int kq;
77
78 static const file_info_t *last;
79
80 /*
81 * forward -- display the file, from an offset, forward.
82 *
83 * There are eight separate cases for this -- regular and non-regular
84 * files, by bytes or lines and from the beginning or end of the file.
85 *
86 * FBYTES byte offset from the beginning of the file
87 * REG seek
88 * NOREG read, counting bytes
89 *
90 * FLINES line offset from the beginning of the file
91 * REG read, counting lines
92 * NOREG read, counting lines
93 *
94 * RBYTES byte offset from the end of the file
95 * REG seek
96 * NOREG cyclically read characters into a wrap-around buffer
97 *
98 * RLINES
99 * REG mmap the file and step back until reach the correct offset.
100 * NOREG cyclically read lines into a wrap-around array of buffers
101 */
102 void
forward(FILE * fp,const char * fn,enum STYLE style,off_t off,struct stat * sbp)103 forward(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
104 {
105 int ch;
106
107 switch(style) {
108 case FBYTES:
109 if (off == 0)
110 break;
111 if (S_ISREG(sbp->st_mode)) {
112 if (sbp->st_size < off)
113 off = sbp->st_size;
114 if (fseeko(fp, off, SEEK_SET) == -1) {
115 ierr(fn);
116 return;
117 }
118 } else while (off--)
119 if ((ch = getc(fp)) == EOF) {
120 if (ferror(fp)) {
121 ierr(fn);
122 return;
123 }
124 break;
125 }
126 break;
127 case FLINES:
128 if (off == 0)
129 break;
130 for (;;) {
131 if ((ch = getc(fp)) == EOF) {
132 if (ferror(fp)) {
133 ierr(fn);
134 return;
135 }
136 break;
137 }
138 if (ch == '\n' && !--off)
139 break;
140 }
141 break;
142 case RBYTES:
143 if (S_ISREG(sbp->st_mode)) {
144 if (sbp->st_size >= off &&
145 fseeko(fp, -off, SEEK_END) == -1) {
146 ierr(fn);
147 return;
148 }
149 } else if (off == 0) {
150 while (getc(fp) != EOF);
151 if (ferror(fp)) {
152 ierr(fn);
153 return;
154 }
155 } else
156 if (bytes(fp, fn, off))
157 return;
158 break;
159 case RLINES:
160 if (S_ISREG(sbp->st_mode))
161 if (!off) {
162 if (fseeko(fp, (off_t)0, SEEK_END) == -1) {
163 ierr(fn);
164 return;
165 }
166 } else
167 rlines(fp, fn, off, sbp);
168 else if (off == 0) {
169 while (getc(fp) != EOF);
170 if (ferror(fp)) {
171 ierr(fn);
172 return;
173 }
174 } else
175 if (lines(fp, fn, off))
176 return;
177 break;
178 default:
179 break;
180 }
181
182 while ((ch = getc(fp)) != EOF)
183 if (putchar(ch) == EOF)
184 oerr();
185 if (ferror(fp)) {
186 ierr(fn);
187 return;
188 }
189 (void)fflush(stdout);
190 }
191
192 /*
193 * rlines -- display the last offset lines of the file.
194 */
195 static void
rlines(FILE * fp,const char * fn,off_t off,struct stat * sbp)196 rlines(FILE *fp, const char *fn, off_t off, struct stat *sbp)
197 {
198 struct mapinfo map;
199 off_t curoff, size;
200 int i;
201
202 if (!(size = sbp->st_size))
203 return;
204 map.start = NULL;
205 map.fd = fileno(fp);
206 map.mapoff = map.maxoff = size;
207
208 /*
209 * Last char is special, ignore whether newline or not. Note that
210 * size == 0 is dealt with above, and size == 1 sets curoff to -1.
211 */
212 curoff = size - 2;
213 while (curoff >= 0) {
214 if (curoff < map.mapoff && maparound(&map, curoff) != 0) {
215 ierr(fn);
216 return;
217 }
218 for (i = curoff - map.mapoff; i >= 0; i--)
219 if (map.start[i] == '\n' && --off == 0)
220 break;
221 /* `i' is either the map offset of a '\n', or -1. */
222 curoff = map.mapoff + i;
223 if (i >= 0)
224 break;
225 }
226 curoff++;
227 if (mapprint(&map, curoff, size - curoff) != 0) {
228 ierr(fn);
229 exit(1);
230 }
231
232 /* Set the file pointer to reflect the length displayed. */
233 if (fseeko(fp, sbp->st_size, SEEK_SET) == -1) {
234 ierr(fn);
235 return;
236 }
237 if (map.start != NULL && munmap(map.start, map.maplen)) {
238 ierr(fn);
239 return;
240 }
241 }
242
243 static int
show(file_info_t * file)244 show(file_info_t *file)
245 {
246 int ch;
247
248 while ((ch = getc(file->fp)) != EOF) {
249 if (last != file && no_files > 1) {
250 if (!qflag)
251 printfn(file->file_name, 1);
252 last = file;
253 }
254 if (putchar(ch) == EOF)
255 oerr();
256 }
257 (void)fflush(stdout);
258 if (ferror(file->fp)) {
259 fclose(file->fp);
260 file->fp = NULL;
261 ierr(file->file_name);
262 return 0;
263 }
264 clearerr(file->fp);
265 return 1;
266 }
267
268 static void
set_events(file_info_t * files)269 set_events(file_info_t *files)
270 {
271 int i, n = 0;
272 file_info_t *file;
273 struct timespec ts;
274 struct statfs sf;
275
276 ts.tv_sec = 0;
277 ts.tv_nsec = 0;
278
279 action = USE_KQUEUE;
280 for (i = 0, file = files; i < no_files; i++, file++) {
281 if (! file->fp)
282 continue;
283
284 if (fstatfs(fileno(file->fp), &sf) == 0 &&
285 (sf.f_flags & MNT_LOCAL) == 0) {
286 action = USE_SLEEP;
287 return;
288 }
289
290 if (Fflag && fileno(file->fp) != STDIN_FILENO) {
291 EV_SET(&ev[n], fileno(file->fp), EVFILT_VNODE,
292 EV_ADD | EV_ENABLE | EV_CLEAR,
293 NOTE_DELETE | NOTE_RENAME, 0, 0);
294 n++;
295 }
296 EV_SET(&ev[n], fileno(file->fp), EVFILT_READ,
297 EV_ADD | EV_ENABLE | EV_CLEAR, 0, 0, 0);
298 n++;
299 }
300
301 if (kevent(kq, ev, n, NULL, 0, &ts) < 0) {
302 action = USE_SLEEP;
303 }
304 }
305
306 /*
307 * follow -- display the file, from an offset, forward.
308 *
309 */
310 void
follow(file_info_t * files,enum STYLE style,off_t off)311 follow(file_info_t *files, enum STYLE style, off_t off)
312 {
313 int active, ev_change, i, n = -1;
314 struct stat sb2;
315 file_info_t *file;
316 FILE *ftmp;
317 struct timespec ts;
318
319 /* Position each of the files */
320
321 file = files;
322 active = 0;
323 n = 0;
324 for (i = 0; i < no_files; i++, file++) {
325 if (file->fp) {
326 active = 1;
327 n++;
328 if (no_files > 1 && !qflag)
329 printfn(file->file_name, 1);
330 forward(file->fp, file->file_name, style, off, &file->st);
331 if (Fflag && fileno(file->fp) != STDIN_FILENO)
332 n++;
333 }
334 }
335 if (!Fflag && !active)
336 return;
337
338 last = --file;
339
340 kq = kqueue();
341 if (kq < 0)
342 err(1, "kqueue");
343 ev = malloc(n * sizeof(struct kevent));
344 if (! ev)
345 err(1, "Couldn't allocate memory for kevents.");
346 set_events(files);
347
348 for (;;) {
349 ev_change = 0;
350 if (Fflag) {
351 for (i = 0, file = files; i < no_files; i++, file++) {
352 if (!file->fp) {
353 file->fp =
354 fileargs_fopen(fa, file->file_name,
355 "r");
356 if (file->fp != NULL &&
357 fstat(fileno(file->fp), &file->st)
358 == -1) {
359 fclose(file->fp);
360 file->fp = NULL;
361 }
362 if (file->fp != NULL)
363 ev_change++;
364 continue;
365 }
366 if (fileno(file->fp) == STDIN_FILENO)
367 continue;
368 ftmp = fileargs_fopen(fa, file->file_name, "r");
369 if (ftmp == NULL ||
370 fstat(fileno(ftmp), &sb2) == -1) {
371 if (errno != ENOENT)
372 ierr(file->file_name);
373 show(file);
374 if (file->fp != NULL) {
375 fclose(file->fp);
376 file->fp = NULL;
377 }
378 if (ftmp != NULL) {
379 fclose(ftmp);
380 }
381 ev_change++;
382 continue;
383 }
384
385 if (sb2.st_ino != file->st.st_ino ||
386 sb2.st_dev != file->st.st_dev ||
387 sb2.st_nlink == 0) {
388 show(file);
389 fclose(file->fp);
390 file->fp = ftmp;
391 memcpy(&file->st, &sb2,
392 sizeof(struct stat));
393 ev_change++;
394 } else {
395 fclose(ftmp);
396 }
397 }
398 }
399
400 for (i = 0, file = files; i < no_files; i++, file++)
401 if (file->fp && !show(file))
402 ev_change++;
403
404 if (ev_change)
405 set_events(files);
406
407 switch (action) {
408 case USE_KQUEUE:
409 ts.tv_sec = 1;
410 ts.tv_nsec = 0;
411 /*
412 * In the -F case we set a timeout to ensure that
413 * we re-stat the file at least once every second.
414 */
415 n = kevent(kq, NULL, 0, ev, 1, Fflag ? &ts : NULL);
416 if (n < 0)
417 err(1, "kevent");
418 if (n == 0) {
419 /* timeout */
420 break;
421 } else if (ev->filter == EVFILT_READ && ev->data < 0) {
422 /* file shrank, reposition to end */
423 if (lseek(ev->ident, (off_t)0, SEEK_END) == -1) {
424 ierr(file->file_name);
425 continue;
426 }
427 }
428 break;
429
430 case USE_SLEEP:
431 (void) usleep(250000);
432 break;
433 }
434 }
435 }
436